There is a need for devices that detect tampering with utility meters. Tampering with utility meters can cause damage to equipment, serious injury, and loss of revenue. Meter tampering typically involves opening the sealed meter cover to either disable the counting/registration device or to divert a resource (such as water or electricity). By diverting the resource past the meter (i.e. bypassing the meter), the resource may be consumed without recordation or registration for billing purposes.
While meters are crafted in a way such that opening the meter cover is difficult, it is not practical or likely possible to create a meter cover that cannot be removed. Indeed, at least one consideration is that meter technician may be required to open the meter cover at some point. Therefore the meter closure cannot be impenetrable. Accordingly, a main strategy in tamper protection is to detect and flag a tamper event. Because meters are periodically read, either in person or remotely, the flagging of a meter tamper event allows for relatively timely indication that tampering has occurred. Upon receiving evidence of a tamper event, the situation can be corrected.
Traditionally, mechanical seals have been placed between the meter base assembly and its cover to inhibit unauthorized access. In such cases, a broken seal can indicate a tamper event. This protection mechanism, although sufficient on meters employing primary mechanical counters, may not provide adequate protection for electronic meters. In particular, electronic meters can often be read remotely or at least without close inspection of the meter. Accordingly, if an electronic meter has the ability to report metering data remotely, there may seldom be an opportunity for a meter technician to observe a broken seal at the location of the meter.
One approach to tamper detection is to place a position sensor on the meter cover. In particular, as is known in the art, electronic meters typically include processing circuitry. Such processing circuitry can record any movement of position of the sensor. However, this solution is only effective when the meter is powered, since the position sensor circuits otherwise lack bias power. Conceivably, a thief could tamper with the meter during a power outage without detection. If the thief replaced the meter cover before power is restored, the position sensor would never detect an issue.
There is a need, therefore, for improved electronic tamper detection that operates in the absence of meter power, and does not require, or at least rely exclusively on, a mechanical seal.